added commas

Co-authored-by: Jonathan <[email protected]>

Author: xhudik

_overviews/scala3-book/methods-most.md

@@ -267,7 +267,7 @@ This method works just like the previous method that used an `if`/`else` express
 
 ## Controlling visibility in classes
 
-In classes, objects, traits and enums Scala methods are public by default, so the `Dog` instance created here can access the `speak` method:
+In classes, objects, traits, and enums, Scala methods are public by default, so the `Dog` instance created here can access the `speak` method:
 
 ```scala
 class Dog: